Posted
by
timothy
on Wednesday November 26, 2008 @05:10PM
from the at-least-it's-cheap dept.

gaijinsr writes "The damage done in what CERN calls the 'S34 Incident' (and what other people call a major explosion in the cryogenics system) is much more serious than originally admitted: The earliest possible restart date is late summer next year, but with some proposed improvements to avoid repetitions of the incident, it looks more like 2010. They kept this pretty quiet up to now, not the kind of information policy I would expect from CERN."

This is a work funded by taxpaid dollars, so it should be kept open and transparent. The author of the article is right in this premise.

But I disagree strongly with her perception of the situation. CERN's earlier statements have only been that they did not know how long repairs would take, but that the earliest LHC could possibly restart would be late spring 2009. This is the first time to my knowledge that they have given an estimate of when they actually expect the accelerator to be ready. There was nothing hidden or hushed up about this.

I once worked at on the LHC at CERN and still have some contacts there and in a couple of conversations have come across some rather interesting bits of information.
The fault has been isolated to a single connector, however the analysis was rather difficult as a large amount of the suspect conductor was vaporized by the current surge.
The wires are supposed to carry 8,700-Amps!!! at full power, the intrinsic resistance in this particular bad joint caused some localized heating which then caused a portion of the conductor to no longer be superconducting. all of the current then passed through a sudden, unexpected load and voile, lots of heat, boiling helium and a chain reaction of nastiness. Looks like the pressure discs ruptured as expected, but they were overwhelmed by the sheer amount of boiling Helium, 6-Tons!, and the vacuum vessel buckled and ruptured causing other magnets to quench. the sheer force of the expansions knocked more than 20 of these steering magnets off of their supports. Slightly more problematic then first reports indeed.
There was always an expectation of shutting down the beam for the Winter as the cost of electricity for the experiment is a major operational consideration and rises prohibitively for the experiment during peak heating season.
Hope that they can fix their problems and catch any other flaws before they attempt to ramp up again. Here's to the exploration of fundamental principles.

The initial cause of the incident was probably a bad weld in a busbar joint. But they'll never know; the entire busbar was vaporized when it lost superconductivity under load.

The quench protection system wasn't designed to properly handle a failure of the superconducting busbar between two magnets. There's an elaborate system to dump the energy from a magnet that's starting to lose superconductivity into a big resistor bank. They expected occasional problems within the magnet windings, but this failure wasn't in a winding. The quench system is being redesigned.

The cryogenic system needs many more pressure relief valves. In this event, 6 tons of liquid helium was vaporized, which is 30,000 cubic meters at 1 atmosphere. That much helium couldn't get out of the existing relief valves fast enough, sizable parts of the plumbing were damaged, and magnets were pushed off their mounts. Now that was just bad pressure-vessel design. They should have had enough relief valves or rupture discs for the worst-case scenario. That would have localized the problem. Given the huge amount of energy in the magnets, in close proximity to liquid helium, in an experimental machine, this could not be a totally unexpected possibility.

More relief valves are going in, which means the whole ring has to be brought up to room temperature and atmospheric pressure for plumbing work.
Then the whole commissioning process has to be repeated, which takes months.

The tunnels are empty of people when power is on, because if all that helium vents, the air is unbreathable. But this event was big enough that it could have affected people in experiment halls at tunnel level. If this had happened during actual use, people could have been killed.

A magnet quench isn't supposed to be a big deal. Early design specs said that restarting after a magnet quench should only take a few hours. Oops.

the Mayan calendar merely resets at that date. similar to how computers were expected to reset at y2k, it was not that they expected the world to end they just did not include dates after that much like our calendar does not include specifically year numbers for after 9999(unless you count adding a digit but in that case you would expect the current year to be specified as 02008). http://www.xkcd.com/509/ is somewhat relevant.

1) CERN's communication has been lacking. Especially in deleting reports immediately after the incident on their eLog that had been open. That was a black eye on their image.

2) Plans change as more information comes in, so no one should be surprised by initial statements saying "The earliest possible date is several months" (which would be the case if no magnets needed replacing) followed by Spring '09 if everything goes well. This is now followed by Summer '09 to just repair the problems and late '09/ early '10 if remedial actions are taken.

3) CERN is changing directors in a month or so. The new director will make the decision of cautious startup vs. remediation and more aggressive startup. My expectation is the latter.

The world can wait an extra year for these results. I feel bad for the students and post-docs who are waiting for the data to emerge, though.

The United States made an attempt at building something similar to the LHC several years ago but funding was cut. It was viewed at the time as a major setback in science and would lead to a brain drain in the United States as scientists went overseas where they could be with better equipment. Funding for the LHC was nearly cut several times amid cries that funding should be focused on "more important" science such as global warming. Part of the reason it got built was precisely because it could show that the EU succeeded where the US failed -- and there's been plenty of rivalry there. Arguably, the reason the EU was brought into existence was to compete with the US. There's a lot of pride tied into making this thing work.

There was a huge political debacle about where the LHC should be built that prevented its construction for several years. So while you can point and say "see? Look at all the cooperation!" the truth is that cooperation took a lot of time and a lot of negotiation. It didn't just happen because scientists are agreeable, friendly sorts that are great with people. And nationalism did, and continues to play a role in the LHCs funding and operational details. That's the nature of international politics -- everybody wants something in return, because there's only one Higgs-boson but there's several hundred positions at the LHC and only a few of them will be paraded through the streets when it's finally found while the rest will toil in obscurity. If you think the nationality of those people isn't important, you're in a dream world. The nationalities of those involved have been very carefully selected.

Bottom line is that they are under a lot of pressure to perform and while it's easy for you and I to understand (as engineers) that these are normal problems... How does it look for the politicians in the middle of a global recession to be looking for "god particles"? Not very and if you were running the show you'd be damn stupid not to be out there glad-handing the purse-holders and assuring them everything is fine. Politics is the reason the LHC could be built in the first place, politics is infused in every major organization -- even scientific ones.

So try and be less idealistic and more realistic. Now, again -- I'm not saying this is why the press release was delayed. I'm just saying it's as plausible a theory as the rest.

CERN is an international organisation (like Interpol, WHO, UN, etc.), located on the border between France and Switzerland (Switzerland is NOT part of the EU either).Buildings are mostly in Switzerland, while most of the tunnel is in France.

CERN predates LHC of something like 30 years.The LHC is built in the tunnel used previously (for 10 to 15 years) by the former main CERN project (LEP: Large Electron Positron Collider).

While the LHC is indeed not an EU project, most of girlintraining's remain valid. Politics and national pride play an important part in the internal workings of CERN, and could well explain the communication policy.

Calling people full of nonsense because they did not get some details right is not very polite, dear Anonymous Coward. Actually, there are quite a few building in Prévessin. And while CERN is definitely not an EU project, it is different from the WHO, or the UN in the sense that it has a geographic definition, it is called the European Organization for Nuclear Research. Some of the funding for CERN related projects, like the grids efforts, comes directly from the EU.

the Mayan calendar merely resets at that date. similar to how computers were expected to reset at y2k, it was not that they expected the world to end they just did not include dates after that much like our calendar does not include specifically year numbers for after 9999

Actually it's even less catastrophic than that. The Mayan long count calendar [wikipedia.org] is based on a hierarchical system of cycles, called kin (1 day), winal (20 days), tun (18 winal), katun (20 tun) and baktun (20 katun). Dates are indicated by giving the position in the relative cycle, so today, November 27, 2008, would usually be quoted as 12.19.15.15.15 in the Long Count calendar. You can check out the conversion formula e.g. in the source code for Fourmilab's calendar converter [fourmilab.ch].

The five-position notation for the long count has a cycle length of 2,880,000 days, or approximately 7885 years, ranging from 11 August 3113 BC (0.0.0.0.0) to October 12, 4772 (19.19.19.17.19). If that isn't enough, there are higher-order cycles as well - a pictun of 20 baktun with a cycle length of some 150000 years, a kalabtun of 20 pictun with a cycle length of 3.15 million years and so on. These are conventionally omitted in notation, because dates from these cycles are rarely met in Mayan astrology (or elsewhere for that matter), but there is a mechanism for expressing them.

Thursday, December 20, 2012 is 12.19.19.17.19, and all that happens on December 21 is that all cycles reset and the baktun gets incremented by one, to 13.0.0.0.0. Some New Age freaks interpreted this as the end of the world because of a rather arcane interpretation of the significance of the 13th baktun cycle in a previous world, but even in 4772 the calendar won't "overflow", it will just shift to the next higher-order cycle.